KR20140116959A - Process for purging propane in a polypropylene manufacturing process - Google Patents

Abstract

The present invention relates to a process for the preparation of polypropylene comprising the steps of a) polymerizing propylene in a polymerization zone, b) recovering a effluent comprising polypropylene, propylene, propane and optionally a solvent from the polymerization zone, c) Optionally a solvent, and a stream comprising propylene and propane, d) optionally recirculating the solvent to the polymerization zone, e) delivering the propylene and propane stream to a splitter, Producing an enriched propane bottom stream comprising propylene and an overhead essentially consisting of recycled propylene; and f) delivering said bottoms stream to a membrane separation zone, wherein permeation with improved propylene content and reduced propane content Liquid, improved propane content and reduced propylene content Step to produce fuzzy having, g) it relates to a method for the purging of the propane in the permeate for producing the polymerization including the step of recirculating to the area, the polypropylene process. In one embodiment, the bottom stream produced in the splitter of step e) is washed in the scrubber to remove contaminants, and the overhead of the scrubber is delivered to the membrane separation zone. The invention also includes a separation zone for withdrawing a polymerization zone, a polypropylene, optionally a solvent, and a stream comprising propylene and propane, a splitter for separating propane and propylene, wherein a membrane separation zone is provided , The membrane separation zone being fed with a bottom of the splitter to produce a permeate liquid which is recycled to the purging and polymerization zone. In one embodiment, a scrubber is inserted between the bottom of the splitters and the membrane separation zone to clean the splitter bottoms stream to remove contaminants, and the overhead of the scrubber is delivered to the membrane separation zone.

Description

PROCESS FOR PURGING PROPANE IN A POLYPROPYLENE MANUFACTURING PROCESS < RTI ID = 0.0 >

The present invention relates to a process for purifying propane in a polypropylene manufacturing process.

In a typical polymerization process, propylene monomers, catalysts and other agents are introduced into the high pressure reactor. The feedstock effluent from the reactor is subsequently conveyed to a flash tank where a stream of raw polymer is recovered for further purification. A stream of overhead gas comprising unreacted monomers is also withdrawn from the flash tank and recycled to the reactor. Thus, the propylene delivered to the reactor is a combination of fresh propylene and propylene that is recycled in the reactor / flash process loop. Freshfeed is a high purity reagent, mostly propane, which has a propylene content of 99 +% and the remaining 1% or less is passed through the reactor unchanged, usually polymer-grade propylene. Although the proportion of inert gas introduced into the reactor loop with the fresh feed in this manner is small, the circulating amount is rapidly generated, reducing catalyst activity and reactor productivity. Propane production is usually adjusted to steady state propane content in the loop in the range of about 5 to 30% by continuously discharging a small amount of overhead gas from the recycle loop.

US 6,271,319 describes a process for preparing polypropylene, including treatment of a vent stream from a polymerization reactor for the recovery of propylene for return to the reactor. The process involves the use of a gas separation membrane to separate propylene from propane in the reactor vent stream. In the membrane separation step, a permeate stream comprising not more than 95% propylene recycled to the polymerization reactor, and a residual stream typically containing at least 30% propane vented from the polymerization process. The membrane separation operates on a concentrated propylene stream.

WO 2005-082957 describes a process for preparing polypropylene. The polypropylene manufacturing process includes contacting the oxidation stream with an olefin forming catalyst to form an olefin stream. The intermediate grade propylene stream is separated from the olefin stream by an intermediate grade propylene stream, preferably containing less than 99.5 wt% propylene, based on the total weight of the stream. In one embodiment, the intermediate grade propylene stream is contacted with a polypropylene forming catalyst to form the propylene and unreacted by-products. Propane is removed from unreacted by-products to form at least one purge stream and a propylene-containing recycle stream. "In general, propane and propylene are recovered through the purge stream, and preferably a substantial portion of the propane is separated from the unreacted propylene so that a substantial amount of propane is recycled to the reaction process. This separation of propane can be achieved by conventional means including distillation or separation using molecular sieves or membranes. " Can be quoted.

WO 2008-084415 relates to a membrane-based separation process of propane and propylene, the process comprising transferring a feed stream comprising propylene and propane to a first membrane, wherein the first membrane is a dew point of propylene, A feed port, a residue port, and a non-permeate port at a high temperature and a pressure of between about 400 psia and about 600 psia, said first membrane having a propylene selectivity of at least 6.5, thereby forming a first non- Wherein at least a portion of the liquid stream is condensed on or around the first membrane; And extracting the first permeate propylene condensed stream, wherein the permeate stream is extracted at a temperature equal to or similar to the feed stream. The propylene propane separation is cited, but there is no connection point with the propylene polymerization zone.

US 2004-000513 discloses a mechanism for economical separation of fluid mixtures. Obviously, the apparatus of the present invention comprises a module using a solid penetration-selective membrane. More specifically, the invention relates to a plurality of membrane modules disposed in a first product family, a second product family, and optionally in one or more intermediate groups. The instrument of the present invention with membrane modules within a plurality of groups is advantageously useful for the simultaneous recovery of a very pure infiltration product and a desired non-infiltration product from a mixture comprising an organic compound. There is no connection point with the propylene polymerization zone.

US 2006-266213 relates to a process for treating a gaseous mixture of at least propylene and propane to separate propylene from propane. The gas mixture comes into contact with the membrane which allows selective penetration of propylene to propane. A propylene-enriched permeate and a propane-enriched dialyzate retentate are formed. The propylene concentration of the permeate in the membrane then decreases through the sweeping gas. This process is used in conjunction with the propylene polymerization zone, but no propylene-propane splitter.

US 2004-182786 discloses an apparatus and process for economical separation of a fluid mixture. Obviously, the apparatus of this invention is an integrated oil distillation and permeation-selective membrane separation mechanism. More specifically, the integrated device comprises an oil distillation column and one or more membrane elements utilizing a solid permeable selective membrane. The processes of the present invention are particularly useful for the simultaneous recovery of very pure permeate products, desired non-permeate streams, and one or more distillation products from a fluid mixture comprising at least two compounds having different boiling point temperatures. There is no connection point with the propylene polymerization zone and the membrane operates on a condensed propylene stream.

FR 2886646 describes a process for separating at least one compound comprising at least one n-paraffin in a hydrocarbon feedstock, wherein: the feedstock stream, or a portion of the stream, comprises at least one n-paraffin and In succession in at least one distillation column comprising a selective membrane and in the at least one membrane separation device in any order; One or more streams are withdrawn from the column and the membrane separator, each of the streams being each concentrated to one of the compounds and at least one of the streams is concentrated to at least one n-paraffin. Facilities for the introduction of this process. In particular, this invention relates to a method and apparatus that allows the classification of petroleum fractions containing hydrocarbon molecules having similar boiling points. There is no connection with the propylene polymerization zone.

WO 2009-106706 describes a propane / propylene separation process utilizing at least one membrane separation apparatus and a distillation column comprising one or more modules operating in series, the membrane separation apparatus being located upstream or downstream of the distillation column , Upstream and downstream. There is no connection with the propylene polymerization zone.

No new methods for purging propane in the polypropylene manufacturing process have been found to date.

It is an object of the present invention to provide a new method for purging propane in a polypropylene manufacturing process.

The present invention

a) polymerizing propylene in the polymerization zone,

b) withdrawing from the polymerization zone an effluent comprising polypropylene, propylene, propane and optionally a solvent,

c) delivering said effluent to a separation zone to produce a stream comprising polypropylene, optionally a solvent, and propylene and propane,

d) selectively recirculating the solvent to the polymerization zone,

e) delivering the propylene and propane streams to a splitter to produce an enriched propane bottom stream comprising overhead and small portions of propylene consisting essentially of propylene recycled to the polymerization zone,

f) delivering said bottoms stream to a membrane separation zone to produce a permeate having an improved propylene content and a reduced propane content and a purge having an improved propane content and a reduced propylene content,

g) recirculating said permeate to said polymerization zone

To a process for purging propane in a polypropylene manufacturing process.

In one embodiment, the bottom stream produced in the splitter of step e) is washed in a scrubber to remove contaminants, and the overhead of the scrubber is delivered to the membrane separation zone.

In one embodiment, only a portion of the splitter bottoms stream, or if there is a scrubber overhead, a portion of the scrubber overhead is delivered to the membrane separation zone and the remaining portion is purged or recycled to the polymerization zone.

In one embodiment, only a portion of the splitter bottoms stream of step e) is washed in the scrubber to remove contaminants, and the overhead of the scrubber is delivered to the membrane separation zone and the remainder is purged or recirculated to the polymerization zone do.

An advantage of the present invention is that the propane-enriched stream is transferred to a membrane separation zone, which is directed to a reduced propylene stream and eventually to a reduced-size membrane separation zone by comparison with a concentrated propylene feed oil.

Another advantage is, of course, that it is the raw material source of the membrane separation zone at high temperature by comparison with the feed oil from another part of the splitter at low temperatures. The higher the temperature, the higher the permeability through the membrane.

Of course propane purging provides purging of other components from the polymerization reactor loop.

In one embodiment, the fresh propylene is delivered to the polymerization zone. Optionally, all or part of the fresh propylene is delivered first to a C3 splitter.

Optionally, the concentrated propane bottom stream from the splitter is recovered above one plate above the bottom and the bottoms are purge at the bottom.

Optionally, all or part of the permeate having a concentrated propylene content from the membrane separation zone is delivered to the C3 splitter.

The present invention also

The polymerization zone,

A separating zone for recovering a stream comprising polypropylene, optionally a solvent, and propylene and propane,

Splitter for separating propane and propylene

To a method for bottleneck removal of a polypropylene manufacturing facility.

The yield of the polymerization zone can be increased by varying operating conditions, such as catalyst, temperature, but the splitter is the bottleneck. An advantageous bottleneck method is to allow the propylene to sink to the bottom and introduce the membrane separation zone fed with the bottom of the splitter, thereby producing a permeate and purge that is recycled to the polymerization zone.

The present invention

The polymerization zone,

A separating zone for recovering a stream comprising polypropylene, optionally a solvent, and propylene and propane,

A splitter for separating propane and propylene (also referred to as a C3 splitter)

Lt; / RTI >

A membrane separation zone is provided and the membrane separation zone is fed with a splitter bottom to produce a permeate which is purged and recycled to the polymerization zone.

In one embodiment, a scrubber is inserted between the splitter bottom and the membrane separation zone stream to clean the splitter bottoms stream to remove contaminants, and the overhead of the scrubber is delivered to the membrane separation zone.

In one embodiment, only a portion of the splitter bottoms stream, or if there is a scrubber overhead, a portion of the scrubber overhead is delivered to the membrane separation zone and the remaining portion is purged or recycled to the polymerization zone.

In one embodiment, only a portion of the splitter bottoms stream is cleaned in the scrubber to remove contaminants, and the overhead of the scrubber is delivered to the membrane separation zone and the remaining portion is purged or recycled to the polymerization zone.

In one embodiment, fresh propylene is delivered to the polymerization zone. Optionally, all or part of the fresh propylene is delivered first to the C3 splitter.

Optionally the concentrated propane bottom stream from the splitter is recovered above one plate above the bottom and the heavy materials are purged at the bottom.

Optionally, all or part of the permeate having a concentrated propylene content from the membrane separation zone is delivered to the C3 splitter.

The advantage of this method of removing bottlenecks compared to removing existing splitter and providing a larger splitter is that cost savings are realized as well as shortening the pause period of the polymerization, It is possible to build a zone.

Fig. 1 shows an embodiment of the present invention.

1 shows an embodiment of the present invention. (1) is a polymerization zone, and (2) is a fresh propylene inlet as well as catalysts and other components effective for polymerization. (3) is a effluent comprising polypropylene, propylene, propane and optionally a solvent when polymerization is carried out in a solvent other than propylene. (3) is delivered to the separation zone thereby producing polypropylene, optionally a stream (4) comprising a solvent (not shown in FIG. 1) and propylene and propane. The stream 4 produces an enriched propane bottoms stream 5 comprising a small portion of propylene and an overhead 9 consisting essentially of propylene delivered to a splitter and thereby recycled to the polymerization zone 1. The bottoms stream 5 produced in the splitter is optionally washed, for example using a chemical agent suspended or dissolved in oil in a scrubber to remove contaminants, and the overhead 6 is delivered to the membrane separation zone. The membrane separation zone produces a permeate (8) with an improved propylene content and a reduced propane content and produces a purge (7) with an improved propane content and a reduced propylene content, the permeate (8) being recycled to the polymerization zone do. Optionally all or part of the propylene propylene is delivered first to the C3 splitter. Optionally, stream 5, concentrated propane bottoms stream is recovered above one plate above the bottom and the heavy materials are purged at the bottom. Optionally, all or part of stream 8 with a concentrated propylene content is delivered to a C3 splitter.

With respect to the polymerization zone of step a), the term polypropylene used in the present invention refers to homopolymers of propylene in the unsubstituted and substituted (such as halogenated) forms, propylene copolymers (e.g. having ethylene or butylene) Propylene terpolymer. The process provides selective purging of propane from the polymerization reactor loop. By means of the reactor loop, we are referring to a configuration in which at least a portion of the effluent stream from the polymerization reactor is recycled directly or indirectly to the reactor. The process can be applied to a propylene polymerization loop in which propylene is fed to the reactor and propylene and propane are present in the effluent from the reactor. The main purpose of the process is to remove the propane from the reactor loop while regulating the loss of propylene and return the recovered propylene as feed to the reactor. Rigid components up to ethylene and ethane are purged before the C3 splitter.

The fresh propylene is delivered to the polymerization zone and polymer-grade propylene having a propylene content of 99% or more, for example 99.5%, is typical but not essential. Catalysts, stabilizers, inhibitors, solvents or other components may be introduced into the polymerization zone as required according to the particular polymerization technique in use. One or more reactors may be involved in the process using individual reactors while performing the same or different device operations. The articles of manufacture may be of any type, including, but not limited to, homopolymers such as medium or high impact homopolymers, substituted homopolymers including halogenated, random and block copolymers of ethylene and propylene, Of a propylene polymer.

The polymerization of propylene may be carried out in liquid or vapor phase. Suitable catalysts are titanium chloride and alkyl aluminum chloride.

The gas phase process is usually carried out at a high pressure of 30 to 40 barg and at a temperature of about 70 to 90 占 폚. In the gas phase process, propylene is introduced into the reactor as a liquid. Propylene can be evaporated in the reactor to maintain the reaction temperature at a moderately low level. The polymer is formed as a powder admixed with propylene gas and is separated from the gas by one or more cyclone separators at the top of the reactor vessel. Unreacted propylene, propane and all other lightweight contaminants are recovered in the reactor and cooled and then liquefied and recirculated in the heat exchanger.

In a liquid phase process, propylene, a catalyst and a solvent such as hexane are introduced into a reactor operating at high pressure of 3 to 50 barg and at a temperature of about 70 占 폚. In this case, the polymer is formed as particles floating in the solvent, and the resulting slurry is recovered and separated for polymer purification and monomer recycle.

It is clear that the reactor operating conditions and functions are not critical to the present invention and may vary and vary from plant to plant. Thus, the scope of the present invention encompasses all propylene polymerization reactor types and operating conditions consistent with the production of a propylene / propane purge stream following the membrane separation process associated with the splitter described below.

With respect to the separation zone of step c), the effluent resulting from step b) can be either gaseous or liquid. Techniques that can be used for effluent treatment include flashing, cooling / condensation, distillation, absorption, or a combination of these, depending on whether the effluent from the polymerization zone is liquid or gaseous and on what other components are present. Physical separation of the powder or particle stream from the gas stream or physical separation of the liquid stream from the gas stream may be performed with a simple gravity separator, cyclone separator, or any other convenient type. All these techniques and equipment are familiar and readily available.

As a typical but non-limiting example, if the effluent is a liquid, the liquid may first go to one or more flash stages. Typically, flashing is achieved by lowering the pressure of the liquid, whereby a portion of the liquid is essentially transiently converted to vapor. This can be done by transferring the liquid through the expansion valve to the receiving tank or chamber, or to all other types of phase separation vessels, for example. The released gas can escape from the top of the chamber and the remaining liquid can be recovered from the bottom. Flashing may be performed in a single step, but is preferably performed at two or more steps at progressively lower pressure. The fraction containing the polymer is recovered from the bottom of the flash tank and delivered for polymer clarification and finishing as is known in the art. As mentioned above, in a liquid phase process, the reactor effluent may contain hydrogen and may include hydrogen added as an inert diluent to control the polymerization, so that in this case the flash overhead stream may contain propylene, propane, hexane, hydrogen and Small amounts of other light hydrocarbons, and agents that could be added to facilitate polymerization. This stream may be re-liquefied and subsequently distilled to split hexane and other C4 + hydrocarbons from the propylene, propane, and other lightweight components as overhead stream as a bottom stream. This overhead stream then forms a stream and is delivered to the C3 splitter.

As a second, but non-limiting example, when the polymerization occurs in a gaseous phase, the reaction effluent is a mixture of polymer powder and propylene and other gases. This mixture is separated by going through one or more cyclone separators through tubes inside the reactor itself. The powder phase is removed for finishing. Unreacted propylene, propane and all other lightweight contaminants are recovered in the gas phase from the reactor, streamed and delivered to a C3 splitter. The reactor feed may be liquid in this case, so that the recycle stream must be cooled and condensed to return to the liquid form before returning to the reactor inlet.

With respect to the splitter of step e), this is advantageously one distillation column or an arrangement of two or more distillation columns. The splitter is known per se. The propylene-propane inlet stream from step c) contains up to 30w% propane, advantageously from 0.5wt% to 30w%. In one embodiment, the stream comprises 0.5 to 20 wt%, advantageously 0.5 to 15 wt%, preferably 0.5 to 10 wt% of propane. The inlet stream of the splitter may also include lighter components such as H2, CH4, C2H4 and C2H6. Advantageously, they are purged before the splitter. The proportion of propylene at the bottom of the splitter can be up to 40w% (which means 60w% propane) and advantageously from 1 to 40w%. In one embodiment, the proportion of propylene may be from 1 to 30w% and advantageously from 1 to 20w%. In another embodiment, the proportion of propylene may range from 1 to 20 wt%. The overhead can have at least 99.5w% propylene (which means 0.5% propane). By way of example, a splitter producing an overhead with a propylene content of 99.5w% and a bottom yielding a propylene content of 35w% and a propane content of 65w% operates at a pressure of 16 bar and a lower temperature of 50 ° C.

With respect to the optional scrubber, it is possible to use any at least one chemical agent capable of removing contaminants from the splitter bottoms stream to prevent fouling of the membrane in the membrane separation zone, It can be a container. The splitter bottom stream and the chemical agent are brought into contact in the scrubber for cleaning. For example, a splitter bottom stream may be introduced at the bottom or near the bottom of the scrubber and then contacted, while the chemical agent is introduced at the top of the scrubber or near the top of the scrubber, And is delivered to the membrane separation zone. For example, a splitter bottom stream can simply bubble through this chemical agent or its solution. Preferably, the scrubber is a continuously stirred tank reactor or shower tray type gas / liquid contactor. Most preferably, the scrubber is a gas / liquid contactor of the type of a shower tray.

Regarding the conditions in the scrubber, the internal temperature preferably exceeds the boiling point of the splitter bottom stream. When delivering the splitter bottom stream to the contact vessel, the splitter bottom stream may be heated to avoid condensation in the scrubber.

The contaminants contained in the splitter bottom stream to be removed in the scrubber are at least one organoaluminum compound selected from the group consisting of the organoaluminum compounds represented by the general formula R _{3 -n} AlX _n (I) _wherein each R is one to ten Each X is independently selected from halogen atoms, and n is 0, 1 or 2; alkylalumoxanes wherein alkyl is selected from alkyl having from one to ten carbon atoms; And a blend of both. Preferably R is alkyl having one to six carbon atoms, such as methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, tert- butyl, pentyl and hexyl. Most preferably R is ethyl. Preferably X is selected from the group consisting of fluorine, chlorine, bromine and iodine. Most preferably, X is chlorine. Preferably, n is 0 or 1. Most preferably, n is zero.

Exemplary organoaluminum compounds purified according to the present invention include trimethylaluminum (Me ₃ Al), triethylaluminum (often called "TEAL", Et ₃ Al), tri-n-propylaluminum (nPr ₃ Al) -propyl aluminum (iPr ₃ Al), aluminum tree -n- butyl (nBu ₃ Al), tri-iso-butyl aluminum (often referred to as the _{"TIBAL", iBu 3 Al)} , tree -sec- butyl aluminum (Al secBu ₃ ). Triethylaluminum is the most preferred organoaluminum compound.

Alkylalumoxanes can be produced by hydrolysis of each trialkylaluminum. Examples of preferred alkylalumoxanes include methylalumoxane (MAO), ethyllalumoxane, n-propyllalumoxane, iso-propyllalumoxane, n-butyllalumoxane, iso-butyllalumoxane, sec-butyllalumoxane and octyllalumoxane. Methyllalumoxane (MAO) is the most preferred.

The chemical agents used in the current process must be able to react with these organoaluminum compounds.

The term " capable of reacting "for the purposes of this application is used to indicate that the equilibrium between the reactants, i.e., the chemical agent and the organoaluminum compound, and the product is almost entirely on the product side. Preferably, at least 90 mol%, more preferably at least 95 mol%, even more preferably at least 97 mol%, and most preferably at least 99 mol% of the initial amount of reactant are present in the product .

Preferably, the chemical agent is at least one selected from the list consisting of HX ¹ , X ¹ -A ¹ -X ² , X ¹ -A ¹ -A ² -X ² and X ¹ -A ³ = A ⁴ -X ² Lt; RTI ID = 0.0 >

- A ¹ and A ² are independently selected from the group consisting of CR ¹ R ² , C = O and NR ¹ , wherein CR ¹ R ² And C = O are preferred and CR ¹ R ² Is the most preferred;

A ³ and A ⁴ are independently selected from the group consisting of CR ¹ , N or both, A ³ and A ⁴ are the aromatic ring or the carbon-forming moiety of the condensed ring system; Of these, it is preferred that A ³ and A ⁴ are CR ¹ or A ³ and A ⁴ are carbon-forming part of a cyclic ring system or a condensed ring system;

- X ¹ And X ² Is ^{OR 1, SR 1, = NR} 1, NR 1 R 2, PR 1 R 2, C (= O) R 1, C (= O) OR 1, OC (= O) R 1, C (= O) NR ¹ R ² and NR ¹ C (= O) there is independently selected from the group consisting of R ^2, it is from ^{OR 1, = NR 1, NR} 1 R 2, C (= O) OR 1 , and C (= O) NR ¹ R ² is preferred;

- R ¹ And R ² It is chosen independently from hydrogen, alkyl, aryl, substituted alkyl and the group consisting of substituted aryl, wherein the substituted alkyl represents an alkyl substituted with a X ¹ substituted aryl denotes a substituted aryl group as X ^1;

However, HX ¹ Is not HOH.

The elements A ¹ , A ² , A ³ , A ⁴ , X ¹ , X ² , R ¹ and R ² May be selected so that a saturated or unsaturated ring of one or more, preferably six, is formed. Optionally, these rings can also be condensed. For example, at component X ¹ -A ¹ -X ^2, at component A ¹ , and at component X ¹ -A ¹ -A ² -X ² , component A ¹ or component A ² or both may be a cyclohexyl ring. Alternatively, for example, when A ¹ and A ² are both CR ¹ R ² A ¹ -A ¹ -A ² in the substituent X in -X ² R ¹ Can all form - (CH ₂ -) ₄ -, resulting in a cyclohexyl ring. Alternatively, for example, the compound X ¹ -A ³ = A ⁴ -X ² in which A ³ and A ⁴ form an ortho-distributed benzene ring as shown in the following formula (II). Alternatively, for example, in X ¹ -A ³ = A ⁴ -X ² , the component X ¹ = NR ¹ And A ³ and A ⁴ can be CR ^{1 '} and CR ^{1 "in which} R ¹ , R ^1' and R ^{1 "} are selected such that the resulting compound is a quinoline-derivative as shown in the following formula (III) have.

As shown in formula (III), = NR < ^{1 >} Quot; may indicate that the nitrogen atom forms part of a aromatic ring or aromatic condensed ring system.

R^One And R² : When they are substituted alkyl: preferably R^One And R² (-CH₂-CH₂-O)_m-R³, (-CH₂-CH₂-S)_m-R³, (-CH₂-CH₂-NR³)_m-R³, (-CH₂-CH₂-PR³)_m-R³, (-CH₂-C (= O)_m-R³, (-CH₂-C (= O) O)_m-R³, (-CH₂-OC (= O))_m-R³, (-CH₂-C (= O) NR³)_m-R³ And (-CH₂-NR³C (= O))_m-R³Wherein m is a number ranging from 1 to 400, and in one aspect 1, 2, or 3, and R³ Is selected from the group consisting of hydrogen, aryl and alkyl having from 1 to 40 carbon atoms. R³ , The preferred aryl is phenyl.

R ¹ And R ² : When they are substituted aryl: preferably R < ^{1 >} And R ² It is _{- (- Ph-O) m} -R 3, (-Ph-S) m -R 3, (-Ph-NR 3) m -R 3, (-Ph-PR 3) m -R 3, (- Ph-C (= O)) m -R 3, (-Ph-C (= O) O) m -R 3, (-Ph-OC (= O)) m -R 3, (-Ph-C ( = O) NR ³ ) _m -R ³ and (-Ph-NR ³ C (= O)) _m -R ³ where Ph is phenylene and m is 1 from the number in the range of up to 400, and the one in the first, second, or third aspect, R ³ Is selected from the group consisting of hydrogen, aryl and alkyl having from 1 to 40 carbon atoms. More preferably R < ^{1 >} And R ² is _{- (- Ph-O) m} -R 3, (-Ph-NR 3) m -R 3, (-Ph-C (= O) O) m -R 3, (-Ph-OC ( ^{_{= O)) m -R 3,}} (-Ph-C (= O) NR 3) m -R 3 and ^{(-Ph-NR 3 C (=} O)) is independently selected from the group consisting of _m -R ³ . R ³ , The preferred aryl is phenyl.

R ¹ And R ² The most preferred aryl is ortho-phenylene. According to the IUPAC-naming scheme, the term "phenylene" is a bivalent radical of benzene, the radical of which has the general formula C ₆ H ₄ . Ortho- phenylene may be shown by a _{"1,2-C 6 H 4"} .

More preferably, the chemical agent is ^{X 1 -CR 4 R 5 -X 2} , X 1 -NR 6 -X 2, X 1 -C (= O) -C (= O) -X 2, X 1 - CR ⁴ R ⁵ -CR ⁴ R ⁵ -X ^2, and X ¹ -CR ⁷ = CR ⁷ -X ² , wherein

- X ¹ And X ² Is ^{OR 1, SR 1, = NR} 1, NR 1 R 2, PR 1 R 2, C (= O) R 1, C (= O) OR 1, OC (= O) R 1, C (= O) NR ¹ R ² and NR ¹ C (= O) is independently selected from the group consisting of R ^2, among them ^{OR 1, = NR 1, NR} 1 R 2, C (= O) OR 1 , and C (= O) NR ¹ R ² is preferred;

- R ¹ And R ² Is chosen independently, at this time, the substituted alkyl represents an alkyl substituted with a X ¹ substituted aryl denotes a substituted aryl with X ¹ preferably from the group consisting of hydrogen, alkyl, aryl, substituted alkyl and substituted aryl Lt; / RTI > is as defined above;

- R ⁴ And R ⁵ Is independently selected from the group consisting of hydrogen, alkyl, aryl, substituted alkyl and substituted aryl, as defined above, in 1, 2, or 3 moles; All R < ⁴ > groups on the same carbon atom or adjacent carbon atoms And R ⁵ Saturated, unsaturated, preferably six, ring of cyclohexyl is preferred;

R ⁶ is substituted alkyl as defined above and m is 1, 2, or 3, and is hydrogen, alkyl, aryl, substituted alkyl;

- R ⁷ Is selected from the group consisting of substituted alkyl as defined above and m is 1, 2, or 3, and hydrogen, alkyl, aryl, and substituted alkyl; The two groups R < ⁷ > May be saturated or unsaturated, preferably six rings, of which cyclohexenyl and phenylene are preferred.

 Even more preferably, the chemical agent is selected from the group consisting of the following classes of compounds:

(A) HO-CH ₂ -CH ₂ -O- (CH ₂ -CH ₂ -O) _m -H, wherein m is a number from 0 to 400;

(B) (R ⁸ OOC-CH ₂ -) ₂ N-CHR ⁹ -CHR ⁹ -N (-CH ₂ -COOR ⁸ ) _{2 wherein} R ⁸ Is selected from the group consisting of hydrogen, aryl and alkyl having from 1 to 40 carbon atoms; More preferably R < ^{8 >} Is selected from the group consisting of hydrogen, methyl, ethyl, propyl, butyl and tert-butyl, most preferably R ⁸ Is hydrogen; In this case, R ⁹ Is hydrogen or -CH ₂ -CH ₂ -, and;

(C) (HOOC-CH ₂ -) ₂ N-CHR ⁹ -CHR ⁹ -N (-CH ₂ -COOH) _{2 wherein} the metal is preferably Na, wherein R ⁹ Is hydrogen or -CH ₂ -CH ₂ -, and;

(D) p is an in the range of from 1 to 30, more preferably in the range of 20 from 10, and q is 0, 1, 2 or formula _{(C p H 2p +1) q} N (CH 2 -CH 2 - OH) _{3- q} ethoxylated alkylamine;

_{(E) N (CH 2 -COOH} ) 3, R 10 N (CH 2 -COOH) 2, R 10 2 N (CH 2 -COOH) and each sodium salt, where R ¹⁰ Is selected from the group consisting of hydrogen, aryl and alkyl having from 1 to 40 carbon atoms;

(F) X ³ -A ⁵ -X ⁴ - (-A ⁶ -X ⁴ ) _n -X ⁵ _wherein R ⁵ And R ⁶ Is _{-CH 2 -CH 2 -, -CH =} CH- , and can be selected independently from the group consisting of ortho-phenylene; At this time, X ³ And X ⁵ Is independently OX ⁶ or NX ⁶ X ⁷ , X ⁴ is O or NX ⁶ , X ⁶ and X ⁷ are independently selected from the group consisting of -CH ₂ -COOR ¹¹ , -CH ₂ -CH ₂ -OR ¹¹ , -CH ₂ -CH ₂ -NR ¹¹ ₂ and -CH ₂ -C (= O) NR ¹¹ ₂ , wherein n is in the range from 0 to 400, more preferably n is from 1 to 10 , And even more preferably n is 0, 1, 2, 3, 4 or 5, most preferably n is 1 or 2, wherein R < ¹¹ > Is selected from the group consisting of hydrogen, aryl and alkyl having from 1 to 40 carbon atoms; More preferably R < ¹¹ > is selected from the group consisting of hydrogen, aryl and alkyl having from 1 to 10 carbon atoms; Most preferably R < ¹¹ > Is hydrogen; At this time, the continuous unit -CH ₂ -CH ₂ -X ⁴ Lt; / RTI > may be different;

(G) formula ^{R 12 -C (= O) -CR} 13 R 14 -C (= O) -R 15 or formula ^{X 6 -C (= O) -CR} 13 R 14 -C (= O) -X 7 Beta-diketone and beta-diketone derivatives, wherein X ⁶ And X ⁷ Are independently OR ¹² or NR ¹² R ^13, wherein R ¹² , R ¹³ , R ^14, and R ¹⁵ Is selected from the group consisting of hydrogen, aryl and alkyl having from 1 to 40 carbon atoms; Preferably hydrogen, aryl and alkyl having from 1 to 10 carbon atoms;

(H) 1, 2-dihydroxybenzene; And

(J) 8-X ⁸ -quinoline, wherein X ⁸ R ¹⁶ is selected from the group consisting of hydrogen and methyl Together with NR < ¹⁶ > ₂ and OH, with hydrogen being preferred.

(A) include glycols and polyethylene glycols, which preferably have a molecular weight of at least 100 and at most 5000, more preferably at most 4000 or 3000, even more preferably at most 2000, and Most preferably at most 1000 g / mol.

Specific examples of (B) and (C) include (HOOC-CH ₂ ) ₂ N-CH ₂ -CH ₂ -N (CH ₂ -COOH) ₂ (ethylenediaminetetraacetic acid, EDTA, CAS- , cyclohexanediamine-tetraacetic acid and their respective di-sodium salts.

Specific examples of (D) has the general formula _{(C p H 2p +1) N} (CH 2 -CH 2 -OH) will include a compound of the screen _2, where p is from ₁₂ 18 (N- (C 12 - a _{C 18 alkyl) bis (2-} hydroxyethyl) amine, CAS-number 71786-60-2). These compounds include, for example, Atmer 163 (CAS-number 107043-84-5) or Armostat 400 (N- (C ₁₂ -C ₁₄ alkyl) bis (2-hydroxyethyl) amine, CAS-number 61791-31-9) Is commercially available as Armostat 300 (N- (C ₁₄ -C ₁₈ alkyl) bis (2-hydroxyethyl) amine, CAS-number 61791-44-4).

(E) include N (CH ₂ -COOH) ₃ (nitrilotriacetic acid, CAS-number 139-13-9) and the respective sodium salt.

(F) include (HOOC-CH ₂ ) ₂ N-CH ₂ -CH ₂ -N (CH ₂ -COOH) -CH ₂ -CH ₂ -N (CH ₂ -COOH) ₂ (diethylenetriaminepentaacetic acid, DTPA , CAS-number 67-43-6), (HOOC-CH ₂ ) ₂ N- (CH ₂ -CH ₂ -O) ₂ -CH ₂ -CH ₂ -NCH ₂ -COOH ₂ (ethylenebis (oxyethylenenitrilo) tetra-acetic acid, EGTA, CAS -number 67-42-5), (HOOC-CH 2) 2 N- (1,2-C 6 H 4) -O-CH2-CH 2 -O- (1,2 _{-C 6 H 4) -N (CH} 2 -COOH) 2 (2,2 '- (ethylenedioxy) dianiline-N, N, N', N'-tetraacetic acid, BAPTA, CAS-number 85233-19-8) (HOOC-CH ₂ ) ₂ N-CH ₂ -CH ₂ -N (-CH ₂ -COOH) -CH ₂ -] ₂ (triethylenetetraminehexaacetic acid, TTHA, CAS-number 869-52-3) CH ₂ ) ₂ N-CH ₂ -CH ₂ -N (CH ₂ -COOH) (CH ₂ -CH ₂ -OH) (N- (2-hydroxyethyl) -ethylenediamine-N, N, ) And each trisodium salt.

Specific examples of (J) include 8-quinolinol and 8-amino-quinoline.

Even more preferably, the chemical agent is selected from type (A) or type (D). Most preferably, the chemical agent is selected from class (D).

Preferably, the chemical agent is suspended or dissolved in a liquid to form a suspension or solution, hereinafter referred to as a " solution ", wherein the liquid is chemically inert with respect to the organoaluminum compound. For example, saturated hydrocarbons such as mineral oil are examples of such chemically inert diluents.

Preferably, the concentration of the chemical agent in the liquid is at least 5 wt%, most preferably at least 10 wt%, relative to the amount of the liquid. Preferably, the concentration is at most 90 wt%, more preferably at most 80 wt%, even more preferably at most 70 wt%, and most preferably at most 60 wt%, relative to the amount of the liquid. It is also possible to use the chemical agent in a pure form, that is, in a state in which the chemical agent is not suspended or dissolved in the liquid. The concentration of the chemical agent in the liquid is expressed as wt% based on the total weight of the solution.

Regarding the membrane separation zone in step f), it can operate in liquid or vapor phase. The membrane apparatus comprises membranes which exhibit substantially higher permeability to propylene than propane. Over the long term, various membrane types and materials have been reported in the prior art, with apparently useful properties for propylene / propane separation.

The following various types of membranes can be used:

There is a carbon film that acts as a very fine sieve that separates based on the difference in molecular size. The inorganic film is characterized by good temperature and chemical resistance. These membranes are commercially available for propylene / propane separation, such as Carbon Membranes Ltd. of Arava, Israel.

PPO (phenyl polyoxide) and derivatives thereof (Ilinitch, O. M., Semin, G.L., Chertova, M. V., Zamaraev, K. I., Novel Polymeric Membranes for Separation of Hydrocarbons, J. Membr. Sci.

Polyimide and polyimide, wherein the polyimide is based on the following chemical: 6FDA-TrMP (6FDA-type dianhydride and trimethylphenylenamine-polyamine) with permeability / selectivity pair favorable for propylene / Type dianhydride (4,4 '- (hexafluoroisopropylidene) diphthaleic acid) (SHIMAZU, A., et al.), Including 6FDA-TeMP (6FDA-type dianhydric acid and tetramethylphenylamine-type diamine). , Miyazaki, T., Maeda, M., Ikeda, K., Relationship between Perinselectivity, Diffusivity, Solubility and Chemical Structure of Propylene and Propane in 6FDA-Based Polyimides, J. Polym. Sci. ) 2525-2536; Tanaka, K., Taguchi, A., Hao, J., Kita, H., Okamoto, K., Transmission and separation characteristics of polyimide membranes for olefins and paraffins, J. Membr. Schi, 121 (1996) 197),

Perfluorinated polyimide,

A polymer film made from a copolymer of tetrafluoroethylene with 2,2,4-trifluoro-5-trifluoromethoxy-1,3-dioxole, which material is available under the trade name Hyflon Ausimont SpA, < / RTI > A number of grades can be purchased with different ratios of dioxol and tetrafluoroethylene units, the second preferred material of this type being commercially available under the trade name Cytop® from Asahi Glass Company, Tokyo, Japan.

Polyamide,

Aromatic polyamide,

Polyetherimide,

Polyvinyl pyrrolidone,

Polycarbonate, and

A copolymer or mixture of polymers using at least one of the recited polymers.

A facilitated-transport membrane can be cited. This includes liquids that selectively, reversibly react with unsaturated hydrocarbons, for example, free silver ions themselves, to selectively transport propylene to the membrane.

WO 2011037820 (A1) describes an improved ionic liquid membrane and describes its preparation for the separation of olefins / paraffins. The membrane comprises an ionic liquid having a metal salt. The ionic liquid is a deep eutectic liquid containing a choline salt selected from choline, chloride / hydroxide / tritate, and phosphatidylcholine. Is a metal salt selected from the group consisting of silver, copper, gold, mercury, cadmium and zinc having anions of chloride, nitrate, tetrafluoroborate, triflate, cyanide, thiocyanide and tetraphenylboron. Ionic liquids are eutectic or so-called deep eutectic liquids. Experimental examples have been tested for methane / ethene separation using choline chloride, urea and silver silver / silver chloride.

Because these preferred polymers are all vitreous and rigid, unsupported polymeric membranes are principally available as single-layer gas-separation membranes. These layers, however, are usually too thick to obtain an acceptable transmembrane flux and preferably comprise a very thin optional layer in which the separation membrane forms part of a thicker structure such as an asymmetric membrane or a composite membrane. A thin skin or coating layer can withstand the separation properties and an integral or discrete microporous support layer can withstand the mechanical strength. If desired, a separate layer can be added to seal the support layer to protect the surface from wear and the like before applying the optional layer. The membrane can be made of flat plates or fibers and can be stored in any convenient module form, including spiral-wound modules, plate-frame modules and potted hollow-fiber modules. The manufacture of all these types of membranes and modules is well known in the art. The flat membrane of the spiral wound module is most preferred.

In one embodiment, when there is only a splitter bottom stream or scrubber overhead, a portion of the scrubber overhead is delivered to the membrane separation zone and the remaining portion is purged or recycled to the polymerization zone. The ratio may vary widely depending on the amount of ethane to be purged and the separation achieved by the membrane separation zone. 20 to 100% of the splitter bottom stream is delivered to the membrane separator.

In an embodiment, only a portion of the splitter bottoms stream of step e) is cleaned in the scrubber to remove contaminants and the overhead of the scrubber is delivered to the membrane separation zone and the remaining portion is purged or recycled to the polymerization zone. For example, 20 to 100% of the splitter bottom stream is delivered to the scrubber and then to the membrane separator.

Regarding the bottleneck removal process, the detailed description is the same as that described above with respect to propane purging in the polypropylene manufacturing process.

[Yes]

The following table describes the stream of polypropylene production bottleneck removal according to FIG. The stream numbers are the numbers in FIG.

Claims (8)

A method of purging propane in a polypropylene manufacturing process,
a) polymerizing propylene in the polymerization zone,
b) withdrawing from the polymerization zone an effluent comprising polypropylene, propylene, propane and optionally a solvent,
c) delivering said effluent to a separation zone to produce a stream comprising polypropylene, optionally a solvent, and propylene and propane,
d) selectively recirculating said solvent to said polymerization zone,
e) delivering a stream comprising propylene and propane to a splitter to produce an enriched propane bottom stream comprising overhead and small portions of propylene essentially consisting of propylene recycled to the polymerization zone,
f) delivering said bottoms stream to a membrane separation zone to produce a permeate having an improved propylene content and a reduced propane content and a purge having an improved propane content and a reduced propylene content, and
g) recirculating said permeate to said polymerization zone
≪ / RTI > wherein the process comprises purging propane in a polypropylene manufacturing process. The method of claim 1, wherein the bottom stream produced in the splitter of step c) is washed in a scrubber to remove contaminants, and the overhead of the scrubber is delivered to the membrane separation zone. How to purge propane in a process. 3. A method according to claim 1 or 2, wherein only part of the splitter bottoms stream, or in the case of scrubber overhead, only a part of the scrubber overhead is delivered to the membrane separation zone and the remaining part is purged or recycled to the polymerization zone, A process for purifying propane in a polypropylene manufacturing process. 3. The method of claim 1, wherein only a portion of the splitter bottoms stream of step e) is washed in a scrubber to remove contaminants, and the overhead of the scrubber is delivered to the membrane separation zone, A method for purifying propane in a recycled, polypropylene manufacturing process. A method for debottlenecking a polypropylene manufacturing facility,
The polymerization zone,
A separation zone for recovering a stream comprising polypropylene, optionally a solvent, and propylene and propane, and
Splitter for separating propane and propylene
Lt; / RTI >
A membrane separation zone is provided wherein the membrane separation zone is fed with a bottom of the splitter to produce a permeate which is purged and recycled to the polymerization zone. 6. The method of claim 5 wherein a scrubber is inserted between the splitter bottom and the membrane separation zone stream to clean the splitter bottoms stream to remove contaminants and the overhead of the scrubber is delivered to the membrane separation zone, Methods for removal. 7. A method according to claim 5 or 6, wherein a portion of the splitter bottoms stream, or only a portion of the scrubber overhead when there is scrubber overhead, is delivered to the membrane separation zone and the remaining portion is purged or recycled to the polymerization zone, A method for removing bottlenecks in a polypropylene manufacturing facility. 6. The method of claim 5, wherein only a portion of the splitter bottom stream is cleaned in the scrubber to remove contaminants, the overhead of the scrubber being delivered to the membrane separation zone and the remainder being purged or recycled to the polymerization zone. A method for removing bottlenecks in a propylene plant.

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